Deal With a Devil
by True Pacifist
Summary: Summary in beginning of chapter-Also published on AO3 Please feel free to leave any feedback or comments
1. Chapter 1

Day by day, time after time, it's the same thing. The same human, the same battles, the same possible outcomes. When the human child decides to have a bad time yet again, another character appears. He's yellow and triangular-and doesn't seem to be completely foreign to how things work in The Underground either.

This time around, Chara had gotten the best of the human. Again. And Sans was going to try and stop them. Again. And was probably going to fail. Again.

Sans was waiting in the usual place, the last corridor before Asgore's location. Wind howled wildly around the hallway, the curtains flapped and the lights flickered. All of this would've seemed perfectly normal given the situation, except this was the first time any of these happened since the timeline was reset.

Sans blew it off as a strange timing error, but even then he couldn't ignore the glowing triangle shape in the floor.

"HIYA!"

A short floating triangle emerged from the ground, wearing a top hat and bow tie. To make this creature even more surreal, he only had one eye.

"...What the hell are you?"

"GOOD QUESTION. AND A UNIQUE ONE TOO-WOAH HEY, DON'T GET AHEAD OF YOURSELF PAL."

Sans was already prepared to fight this thing if he needed to. Of all the timeline reports he had read, they all said nothing about a glowing triangle showing up in the King's castle. Sans already had one hand glowing with his usual blue colored magic.

"THAT'S NEAT. I CAN DO SOMETHING LIKE THAT TOO, SEE?" The triangle snapped his fingers and his hand was suddenly engulfed in blue flame. Now Sans was scared, he took a step back and prepared to attack.

"HAHA, DON'T WORRY, YOU GET USED TO THE BURNING. ANYWAY, SEEMS YOU WANNA KNOW SOMETHING ABOUT LIL OL ME? YOU COULD SAY I'M A MUSE OF SORTS, CALL ME BILL!" He floated down to Sans's height and held out a hand to shake. In response, he took another step back and shoved his hands into the pocket of his jacket.

TO GET TO THE POINT, I'VE BEEN OBSERVING THIS TIMELINE FOR AWHILE NOW. YOU SURE MUST BE FRUSTRATED AT THIS POINT, AREN'T CHA?"

"How...? How do you know...?"

"OH I KNOW LOTS OF THINGS, SAY, WHY WAS THE SKELETON SHAKING? C'MON, YOU KNOW THIS ONE!"

A bad skeleton pun. This was getting too creepy. "B-because something had rattled-"

"IT'S BONES! HA! YOU DO HAVE A GOOD SENSE OF HUMOR!"

"Look, I don't know who or what you are, but I learned awhile ago not to trust small yellow talking creatures, sorry."

Sans tried to banish the mental image of a certain soulless flower.

"OUCH. DISMISSIVE, I BET YOUR BROTHER WOULD'NT HAVE RESPONDED THAT WAY."

Now he had gone too far.

"TO GET TO THE POINT, HOW WOULD YOU LIKE TO SEE HIM AGAIN?"


	2. Chapter 2

Too freaky. _Way_ too freaky. Hundreds of timeline reports never showed or even predicted this…this _thing_ showing up. Sans's magic was quietly raging, ready to burst out at any moment, but just the possibility of Papyrus coming back to life suppressed the anger and replaced it with hope—an emotion Sans hadn't felt for a _very_ long time.

"I'M TAKING YOUR SILENCE AS A SIGN OF INTEREST. YOU SEE, I KINDA HAVE SOME EXPERIENCE WITH FIXING…UNFAIR SITUATIONS." Bill provided a blue-flame image of the human child evaporating, with everyone who had reappearing shortly after.

Sans was willing to listen now, but still suspicious. "Prove it."

With the exception of the two monsters in the area, the whole room turned gray and even the air ceased to move. Sans had become so invested in their conversation that he didn't even notice the human walking towards him from the other side of the hall, despite the unfamiliar creature beside him. And the human too, was frozen.

Bill snapped his fingers and a fiery void opened up in the shape of a triangle behind the human. The wing all of a sudden started howling and the multicolored flames were almost blinding. "KIDS LIKE THESE SHOULD BE BURNING IN HELL, THAT'S WHAT YOU ALWAYS SAY, AND YET IT NEVER HAPPENS. HOW ABOUT I FIX THAT FOR YOU?"

Sans would love to send that child to hell himself, but no matter how hard he tried, their determination got the better of his own laziness. Now a crazy powerful demon—monster—whatever he was, was offering to change everything, to give this timeline a "happy ending."

And deep down, Sans also knew there was something extremely off about this guy, aside from the power and knowledge. Or maybe he was just being paranoid? Just because Flowey was an innocent-looking demon didn't mean every weird yellow monster was.

Or was that just an excuse to be lazy?

Either way, Sans could get his brother back. Papyrus, who foolishly believed that anyone could be a good person if they just tried, Bill could bring him back here and now, Sans could protect him this time. He could fix everything.

 _And_ they'd have the final human soul needed to break the barrier between the Underground and the Surface, if this child even had any soul left.

Right. Of course they'd still have a soul, all a human soul needs to last is determination. And this little shit had proven they have plenty of it.

Now Sans was determined too.

He sighed. "What's the catch? There's gotta be a catch."

"LOOK AT THIS GUY, ANOTHER GREAT QUESTION! ALL I NEED IS FOR YOU TO ALLOW ME TO USE YOUR BODY AS A PASSAGE, SO I CAN, YOU KNOW, EXPLAIN TO EVERYONE WHAT'S GOING ON. ONLY YOU CAN SEE ME, TIME TRAVELER'S SECRET, YA KNOW? IT'LL ONLY BE EVERY ONCE IN AWHILE, YOU'LL STILL BE ABLE TO SEE EVERYTHING THAT'S GOING ON."

If Bill had said this earlier, Sans would've blasted him out of the timeline right then and there. But at this point, Bill could mention taking the Souls and he wouldn't care anymore. Sans just wanted his brother back, his friends back, for this timeline to break out of its loop once and for all.

"You got yourself a deal, weirdo." They shook hands, both covered in blue flame. Sans was already used to the burning, he had been for several timelines now.

"PLEASURE DOIN' BUSINESS WITH YA, NOW TO HOLD UP MY END OF THE DEAL."

The wind froze again. A blinding light filled the corridor; the child didn't even scream as they were sucked into the fiery void, it was more like they were fading away into the light, turning to dust.

The villain was gone, the heroes were back. Everyone was alive now, everyone was safe now.

Papyrus was alive now, and Sans didn't even have to go looking for him.

Bill had disappeared, but Sans could hear his last words echoing: "I'LL LEAVE YOU TWO TO A BROTHERLY REUNION NOW, BYE!"

Another loud voice boomed, one much more familiar.

"SANS? WHAT HAPPENED? WHERE ARE WE? DID I CAPTURE THE HUMAN!?" Papyrus didn't waste any time staying calm.

Sans had never been any happier to hear his brother overreact.


	3. Chapter 3

Sans also had no clue what to say now that Papyrus was back.

He needed to know the truth about the human, there was no doubt about that. And how was Sans going to explain that Papyrus had died? What if he wanted to go after the human again? They were gone, so it didn't really matter anymore, but Papyrus needed to stay safe, not throw himself into danger again.

Sans was so overwhelmed with these thoughts and feelings he didn't notice his own tears.

"SANS? WHAT'S WRONG? WHY ARE YOU CRYING? DID YOU GET HURT-"

Papyrus stopped talking the minute his brother ran over to hug him, sobbing beyond any reason Papyrus could think of. There was only one timeline for him with each reset, he didn't remember, he never remembered. Papyrus didn't investigate time like Sans did, he was too busy staying determined in the present.

"WHAT...WHAT HAPPENED? THERE WAS THAT WEIRD HUMAN, I WAS WAITING FOR THEM JUST OUTSIDE OF SNOWDIN, AND THEN...AND THEN..."

The memories were just out of reach.

"T-they killed you...the little bastard k-killed you, y-you trusted them and they just...turned you to d-dust right then and there."

Sans no longer felt the anger associated with this memory, he had his brother back, Papyrus was alive without having to wait for a reset.

"WHAT? THAT'S IMPOSSIBLE! THE GREAT PAPYRUS DOES NOT DIE! NOTHING GETS PAST ME! THAT HUMAN MUST'VE-"

Only then did Papyrus notice the red human soul floating just above the floor beside them.

"OH NO, SANS, YOU DIDN'T...OR DID THEY...?"

If any part of the explanation was the hardest, it was going to be this part.

Papyrus was innocent and too trusting, he had always wanted to see the best in people even if said person didn't want to show it. Sans didn't have the heart to break his spirit. Death, betrayal, evil, these were all things he was trying to protect Papyrus from, no one deserves to know the dark truth if they can get by without it. Especially not Papyrus, who was willing to spare a human who had very clearly been killing everything in sight.

If Sans explained to Papyrus what happened with Bill, that would be that, Papyrus would believe him. But even though Sans had trusted Bill enough to make a deal with him, he did not want a creature with that much power around his too-trusting brother.

But despite all these things, Sans had to at least tell Papyrus the truth about one thing: the human's intentions, no matter if they could be a good person or not.

"I-I had to, t-they were going to kill everyone else. I couldn't just let them get away with that…y-you're…we're…the only family we have…"

The sadness had cut to rage and back again, to the point where words were failing and Sans no longer cared about explaining anything.

"I…I'VE BEEN A LITTLE FOOLISH, HAVEN'T I? SANS, I'M SO SORRY! I SHOULD'VE CAPTURED THE HUMAN WHILE I HAD THE CHANCE, THEY COULDN'T HAVE BEEN THAT POWERFUL IF YOU WERE ABLE TO…TAKE THEIR SOUL SO EASILY. THE PAIN YOU MUST'VE HAD TO GO THROUGH, HAVING YOUR GREAT BROTHER DISAPPEAR IN THE BLINK OF AN EYE; I CAN'T IMAGINE FACING THAT MYSELF! I'D MISS ME TOO!"

Dramatic, emotional, and slightly egotistical as usual. Sans took it as a good sign that Papyrus refused to say "killed" or anything of the sort.

"Pain" couldn't even begin to describe what Sans had gone through for the past—he'd lost track of the number of resets—but it felt like a lifetime. Even trying to fight the human was like a sort of suicide at this point, there was no point in doing anything if the outcome never got to change a single event, and he had known this from the first reset. In a way, fighting was giving up; even being lazy everyday took more energy than throwing it all away in a series of attacks, knowing that he'd fail every single time.

Sans couldn't count the amount of times he had completely given up this way either.

"Y-you have no idea bro, you really have no idea."

"ALTHOUGH I STILL HAVE TO ASK—HOW AM I ALIVE AND WELL RIGHT NOW IF THAT HUMAN DID SUCH A VIOLENCE?"

Sans started breaking down all over again, and Papyrus quickly decided this was not the time to ask that question.

"LET'S NOT WORRY ABOUT THAT RIGHT NOW, C'MON, LET'S GO HOME, I'M SURE EVERYONE WILL BE DELIGHTED TO SEE US SAFE."

Everyone else being alive again was a different matter entirely, and not one Sans had the emotional energy to explain at the moment, Papyrus would find out soon anyway.

They left the soul in the corridor, soon Asgore would hear word of everyone reappearing, and of the soul, and then he would absorb all seven human souls and break the barrier. Monsters would be free at last, but that wasn't the first thing on Sans nor Papyrus's mind.

Sans just wanted everything to go back to normal; he didn't care about getting to the surface anymore as long as he didn't have to relive the same sequence of events endlessly. And as much as he wanted to believe he had fixed everything, deep down he knew there was a lot more fighting left to do—just hopefully not the kind that would require him to use every ounce of determination he had left.

After all, Sans's end of the deal still needed to be held up.


	4. Chapter 4

Nononono NO, this was NOT part of the plan, everything had gone wrong. At least, it had for Flowey.

Chara was gone; everyone was alive like nothing had ever happened, and worst of all, no reset had occurred. Flowey couldn't reach his save point; it really looked like this was the end of the looping timelines.

What would Flowey do now? That was the only thing he had to keep his life interesting, resetting, experimenting…and just as he got his best friend back, Chara had left again in the blink of an eye.

"EYE. THAT'S FUNNY; I ONLY HAVE ONE EYE TOO!" The voice echoed inside Flowey's head, but the owner of the voice was suddenly hovering right in front of him.

"GAH! Ah, um, I mean…hi!" Flowey quickly regained his false-friendliness shtick, now there was a new person—monster? To play with, he could get behind that. "I'm-"

"ASRIEL, AMIRIGHT? JUST KIDDING, I KNOW I'M RIGHT! YOU CAN DROP THE ACT BY THE WAY, I'VE SEEN IT ALL BEFORE, I CAN'T IMAGINE THE ENERGY IT TAKES TO KEEP THAT UP!"

Usually, Flowey's next move would be to try to scare Bill, but this encounter wasn't the same experience he was used to. This wasn't a naïve human, or a human at all, and whatever this-monster? Was, Flowey didn't need a soul to be scared of its immense power.

"W-what do you want from me?" Flowey shrank, more then he already had.

"THERE YOU GO, FINALLY SHOWING YOUR TRUE COLORS. AS MUCH AS YOU TRY NOT TO BE, YOU'RE SCARED, AND FRANKLY, YOU HAVE REASON TO BE. THINGS ARE GONNA REEEEAAAAAALLLLL WEIRD PRETTY SOON."

Flowey felt one of the only other emotions he had left now. Anger. "What…happened to Chara?!" He didn't bother to morph into one of his "scary faces," he didn't feel the need to hide behind anything right now. No one was going to completely take away the one person that still remembered him.

"I'M PREEEEEEEETTY SURE SKELE-PUN BACK THERE JUST SENT THEM STRAIGHT TO HELL, BUT HEY! LOOK ON THE BRIGHT SIDE! I TOOK THE HUMAN SOUL BEFORE ANYONE ELSE COULD, WE SURE COULD HAVE A LOT OF FUN WITH THIS THING." Bill opened his palm, the tiny red heart-shaped soul floating right above his hand.

Flowey began to tremble; this was all too much like the events before he became a flower. He couldn't absorb the soul this time, he wouldn't, and no good would come out of it, even if destruction was all Flowey had wanted for a long time.

Really he just wanted all this to end.

"I'm not…you wouldn't…I won't…who are you?" Honestly, the least of Flowey's worries was the tiny creature floating in front of him, or so he thought.

"I'M BILL, BUT YOU CAN CALL ME YOUR NEW FRIEND. I DON'T WANT THIS ONE SOUL, I HAVE NO USE FOR IT, HOWEVER I HAPPEN TO KNOW A LITTLE PLANT RIIIIGHT HERE THAT'S BEEN DYING TO HAVE HIS ORIGINAL FORM BACK!"

"I…I don't want it, I-I won't take Chara's soul again…that didn't-"

"END WELL. I KNOW. AND THAT'S WHY YOU'RE STUCK AS YOU ARE NOW, A SOULLESS LITTLE FLOWER WHO WANTS NOTHING MORE THAN TO FEEL AGAIN. LOOK BUDDY, SATAN CHILD ISN'T COMING BACK, BUT MAYBE WITH A LITTLE HELP FROM YOURS TRULY, YOU MIGHT BE ABLE TO SEE THEM AGAIN ANYWAY. I'VE WATCHED THIS TIMELINE FROM THE BEGINNING, EVERY SAVE AND RELOAD, EVERY ALTERNATE ENDING; ANYTHING IS POSSIBLE AS LONG AS YOU HAVE A SOUL. WOULDN'T YOU LIKE TO LEAVE THIS PLACE? GO BACK TO YOUR FAMILY AND CONTINUE ON WITH YOUR LIFE? HOW LONG-"

"Fine! Fine…I-I get it…I just…here, give it to me!" Flowey, for the first time since he could remember, was filled with determination to do something good. There was nothing wrong with wanting your life and your family back, right? And the chance to see Chara again…without them being able to destroy everything.

The tiny soul now lay in front of Flowey, slowly drifting forward; he closed his eyes and waited for his body to come back to him.

Flowey—Asriel, blinked, turned his head, moved his shaking hands in front of his face to remind himself that, yes, he could feel again. Emotions came flooding in all at once; so many that they needed to be blocked out for a second. Asriel could feel Chara's soul spreading throughout him, there was immense power, power that this time, would be used for good.

He found his voice again, and then remembered the "friendly" little creature in front of him. "Thank you…how can I repay you?"

"OH EASY! JUST GUIDE ME TO THE REST OF THE HUMAN SOULS!"


	5. Chapter 5

" _WRONG MOVE BUDDY, YOU SHOULD'VE STOPPED ME WHEN YOU HAD THE CHANCE."_

" _We won't let you get away with this!" The voice was barely recognizable._

" _BUT YOU ALREADY HAVE, IT'S THANKS TO YOU AND ALL THESE OTHER BONEHEADS THAT I GOT TO WHERE I AM NOW, SEE YOU IN MY NEW DIMENSION!"_

 _The wind howled, another fiery void opened up and swallowed everything in sight, the sound of the intense flames was nothing compared to all the screaming and whooshing of monster bodies fading into dust._

" _oh-"_

"Oh no," Sans woke up on the verge of yelling.

A dream, just a dream, right? A really, really weird and crazy dream that felt _very_ real. But no, not that, _this_ was real and how things should be, Papyrus was alive and so was everyone else, the demon was gone and Sans would never have to see them again. No more reason to live in despair, it wouldn't hang over every timeline now, the alternate timelines were gone.

"…maybe I should just chec—"The door burst open before Sans could finish his thought.

"SANS! HOW LONG DO YOU PLAN ON SLEEPING FOR? WE'RE SUPPOSED TO BE HANGING OUT WITH UNDYNE TODAY, REMEMBER? SHE WANTS TO SHOW US SOMETHING CALLED A-KNEE-MAY; APPARENTLY IT HOLDS ALL THE SECRETS TO THE UNIVERSE AND THE SURFACE WORLD! MAYBE WE'LL BE ABLE TO FIND OUT WHAT WAS WRONG WITH THAT STRANGE HUMAN, AREN'T YOU EXCITED?"

"Uh, right, yeah…I'll…I'll be up in a minute bro."

Papyrus left with a twirl of his cape, he didn't see Sans jump up and rummage through one of the only drawers in the room.

"C'mon…that one note…it's gotta be somewhere, it has to have something…"

This was the only code left that Sans hadn't been able to translate yet, a string of random symbols that came with a key Sans always had with him. It came out as a jumble of letters rather than actual words, with every strange vision-like dream he had, there was a cryptic note left behind somewhere that explained it. The same happened with the alternate timelines: vision, note, clue, that's how it always went.

"SANS!"

Sans quickly shoved the note into the pocket of his jacket and followed Papyrus.

Later, at Undyne's house:

"And that's how it ends! They made a movie too, but the ending is pretty awful!" Undyne threw her spear across the room as the anime they were all watching came to a close.

"THAT'S NOT FAIR! SHE JUST WANTED HER FRIEND ALIVE AND WELL. ALTHOUGH I GUESS BECOMING A GODDESS ISN'T THAT BAD EITHER..."

"Riiight, friends, TOTALLY just friends, you keep thinking that, Papyrus."

Sans was in a corner of Undyne's house, staring out the once-broken window. He scribbled the translation of the note over it's code, but no matter how much he stared at it, he couldn't unscramble the letters.

RAEFEHTTSAEBHTIWENOYEE

"SANS! HAVE YOU BEEN PAYING ATTENTION AT ALL? YOU'VE JUST BEEN STARING AT THAT-WAIT, IS THAT...A PUZZLE?"

Sans sighed and nodded in response.

"NO WONDER YOU'RE HAVING TROUBLE, YOU MUST BE UTTERLY STUMPED BY SUCH A DIFFICULT PUZZLE, ONE THAT ONLY THE GREAT PAPYRUS CAN SOLVE! MAY I?"

"Knock yourself out bro," Sans handed Papyrus the note, not expecting much. But it was nice to see Papyrus hyped over a puzzle again.

"What IS that? Let me see!" Undyne looked over Papyrus's shoulder and squinted at the note.

"THIS LOOKS LIKE A SINGLE LINE FROM A CROSSWORD! IT MAY BE IMPOSSIBLE TO SOLVE THIS WITHOUT THE REST OF THE CROSSWORD, BUT HMM...LET'S SEE..."

Undyne let out a victorious "Ah-ha!" And placed one finger below the first four letters, "that's 'fear' spelled backwards, I've got no clue for the rest of it though!" She slapped Papyrus on the back and went to her room to find another anime to watch.

"Y'know, you don't have to try and solve that if you don't want to." Sans said quietly, watching Papyrus stare intensely at the scrape of paper.

"NONSENSE! IT'S MY JOB AS A GREAT BROTHER TO HELP YOU THROUGH THESE TRYING TIMES! NOW...LET'S SEE. THE NEXT FOUR LETTERS SPELLED BACKWARDS TURN INTO 'TTHE,' BUT THAT'S NOT A WORD..."

"Guess its a bit...puzzling huh?" He could've thought of a better pun, but right now he just didn't have the energy to do so.

"SANS THAT WAS EVEN WORSE THEN USUAL, ARE YOU SURE YOU'RE FEELING ALRIGHT?"

"Yeah, I just...I just...its nothing, don't worry about it."

Papyrus put the "puzzle" aside. "HAVE YOU BEEN HAVING THOSE BAD DREAMS AGAIN?"

Sans sighed, "yeah, that's it. Nothing to-"

"FEAR NOT, BROTHER! JUST REMEMBER THOSE DREAMS HAVE NO MEANING, EVERYTHING IS ALRIGHT NOW!"

But they _did_ have a meaning, every single time. Papyrus didn't need to know that, though.

"...you're right, thanks bro. Got anything from that puzzle?"

"WELL, NO. BUT ITS NOTHING WE, THE GREATEST PUZZLE SOLVERS CAN'T FIGURE OUT!" Papyrus picked up the piece of paper again.

"Every four letters, huh? Well what if-"

Undyne burst through the door, holding a stack of DVDs. "Oh my god! Do _I_ have to be the nerdy one here now?" Undyne snatched the code, took a pen, and crossed out out of the t's in "TTHE"

"It's literally just 'THE!" This shouldn't be too hard to figure out for you nerds!"

FEAR and THE. Sans suddenly wasn't so eager to finish the code.

"OOH, I SEE, SO EVERY FEW LETTERS REVERSED SPELLS OUT A NEW WORD? THIS SHOULD BE EASY NOW!"

"Yeah, yeah, but for now, let's watch some anime! I've been dying to see this one!" Undyne took out a DVD and turned her TV back on.

Sans took the note back, he could finish decoding later, when Papyrus wasn't looking.

That night:

Sans had figured out most of the code now, every few letters reversed spelled out a word, and left just enough letters to form another one.

FEAR THE BEAST WITH ONE...the last few letters didn't spell out a word, it came out as 'EEY.'

"Unless..." Sans muttered to himself, writing out a few rearrangements of those three letters.

"EYE."

Only now did the gravity of his mistake settle in.

"Of course. Of-freakin-course. Where is that yellow piece of-?"

Unwillingly, Sans found himself burning the code to a crisp with just a touch of magic, the blue flame brighter than usual.

And then he suddenly felt control of his own powers slip away.


	6. Chapter 6

Sans could see, hear…he still had all senses intact. But no longer could he move his own body.

"OHH BOY, THIS VESSEL'S POWER SURE IS GONNA BE FUN TO PLAY WITH! THANKS FOR MAKING THAT DEAL WITH ME, SKELE-PUN, BUT I'M AFRAID YOU WERE HITTING A LITTLE TOO CLOSE TO HOME JUST NOW. AND LET'S KEEP THE LANGUAGE PG RATED, SHALL WE?" Bill's voice filled Sans's thoughts, although any of those thoughts were now near impossible to make out in the first place.

"Sans" got up and started to leave the house. "YOU SEE, FLOWER SATAN BACK OVER AT THE RUINS WOULDN'T PAY HIS DUES EVEN AFTER I GAVE HIM HIS BODY AND ALL SOURCE OF EMOTION BACK, SO I'M LEAVING HIM BE… _**FOR NOW**_." His voice went from expressive and lighthearted to dark and demonic very quickly.

"Nnnngh…" Sans struggled to regain any sense of control, "You. Why. How…?"

"WHEN YOU SPEND TRILLIONS OF YEARS TRYING TO GAIN CONTROL OF THE SAME UNIVERSE, YOU GET KINDA BORED AND START LOOKING FOR ANOTHER ONE. THE RESETTING TIMELINE CAUGHT MY EYE, AND IT DIDN'T TAKE MUCH INVESTGATION TO FIGURE OUT JUST WHO TO APPROACH. EVERYONE HAS A WEAK POINT, SOMEONE OR SOMETHING THEY'D GIVE UP ANYTHING TO PROTECT, EVEN CONTROL OF THEIR OWN ACTIONS! NOW, I'M GOING TO BRING US DOWN TO THE SOULS—OH, DON'T WORRY, I'LL GIVE YOU YOUR BODY BACK BEFORE ABSORBING THE SOULS—SO YOU CAN ENJOY THE SHOW!" They started to walk towards the caves.

Just a little bit of power, that's all Sans had, enough power to spit out a few anguished words. "S-stop. Get. Out." His eye was slightly glowing, but all magic Sans could muster was now in Bill's control.

"OH YEAH, THAT'S RIGHT…YOU CAN TELEPORT, CAN'T YA? THANKS FOR SUMMONING UP THAT BIT OF ENERGY FOR ME!" The blue magic went from a small swirl to a cyclone shape, spinning rapidly. And by the time the magic had died down, Sans and Bill had teleported away.

Meanwhile…

Asriel's consciousness had gone out in a flash of light once Bill left, and he was now just starting to come to on a bed of golden flowers, words echoed in his head.

" _I-I'm sorry…but I don't know where the souls are."_

" _OH PLEASE, YOU KNOW_ _ **EXACTLY**_ _WHERE THEY ARE! AND WITH HIS SON BACK, I'M SURE KING FLUFFYBUNS WOULDN'T HESITATE TO SHOW THIS WHOLE WORLD'S POWER SOURCE!"_

" _W-what…do you want with the souls anyway? What are you going to do…?"_

" _THAT'S FOR ME TO KNOW AND YOU TO FIND OUT, BUT IT LOOKS LIKE YOU PREFER FINDING OUT THE HARD WAY. SEE YA LATER, KID!"_

Asriel sat up quickly, nearly screaming. He looked around the dark room, down at his own hands, and then at the patch of golden flowers he was sitting on. This is real, he was real, and it appeared that the whole underground was in _huge_ trouble.

"I have to do something…b-but…how-" Footsteps approached, slowly and gently, a familiar sound.

"Oh dear, are you another…hu…man…?" Toriel's voice trailed off upon seeing her dead son alive and well before her.

Asriel scrambled to his feet, shaking "Mom…?" He was almost too scared to look up any further; instead he stumbled into a hug.

Through tears, Toriel spoke: "Asriel…i-is this really you? How…how…? No, I do not want to know that. My dear child, what you must have been through…" She held her son tight, as if he'd fade away once she let go.

"Mom…mom, you're…real right? This…is real. Oh, god, this _is_ real. Mom, we need to find Dad, right now! T-the souls…" Toriel raised a patient hand to stop Asriel from panicking.

"Coming back so suddenly…and something is already wrong?" The little goat monster broke away from the hug, starting hopping up and down.

"We have to go! There was this weird yellow thing…and the souls…Dad's in trouble! Everyone's in trouble!" He began to tug on Toriel's sleeve, and tears kept falling. "I'll explain on the way, but right now…everyone's going to need us very soon. I…I can feel it."

Toriel gently pat Asriel's head "My child, I cannot imagine a problem that we could not fix, come now, the castle is this way…but you should know that your father and I have not spoken for quite some time…"

She took her child's hand and started quickly guiding them throughout the ruins, past Snowdin, into the caves and Hotlands, all while Asriel tried to explain his encounter with Bill and how he came back. He even mentioned his time as a flower, but left out the part about the resets and all the horrible things "Flowey" had done. Asriel wasn't ready to think about that yet, he got chills just from coming across any flowers now. He also wasn't ready to think about the fact that, although Chara was in control of this soul, this wasn't Chara's soul. This soul felt compassion and love, this soul wanted to save everyone, save humanity, which Chara had hated enough to cause two deaths. Even more, if given the chance, and seeing what happened…it looks like they did, until Bill came along.

"How…how did that…thing get so much power?" Asriel muttered this to himself as they came closer and closer to Asgore's house.

Upon getting to the door, Toriel cleared her throat and said, in a very serious voice: "Asgore, are you in there?" She knocked gently, the door was already open.

"The key, the key…Dad always kept the key to the garden in the kitchen, right?" Asriel looked up at his mom, who nodded solemnly.

However, when getting to the key's location, someone had already picked it up. And it was not at all who either of them would've suspected.


	7. Chapter 7

"...Sans?" Asriel spoke slowly, knowing that in this timeline Toriel did not know Sans was the one exchanging jokes with her through the door.

'Sans' slowly turned, swinging the key around one hand with a bit of magic.

"HI THERE! DID YOU SLEEP WELL? HOPE YOU DON'T MIND ME USING YOUR FRIENDS VESSEL FOR A WHILE, SINCE, YA KNOW, YOU DIDN'T WANT TO SHOW ME THE SOULS. BUT THIS GUY RIGHT HERE WAS HAPPY TO MAKE A DEAL WITH ME! ISN'T THAT RIGHT, SKELE-PUN?"

Sans struggled to speak, and had to keep himself from calling Toriel's name, he technically wasn't supposed to know what she looked like yet.

"R-run..." He was barely able to stutter, his eye started glowing again.

"That voice...!" Toriel whispered, reaching out a gentle hand.

Sans saw Bill reach out to teleport again-or possibly do a magical attack on Toriel and Asriel—and started struggling even more than ever. Shaking, switching back and forth between bits of Bill's and his own voice, flashes of magic fading in and out, until Bill called out " ** _ENOUGH_** " in his demonic voice, then cleared his throat and went back to his usual playful one.

"LOOKS LIKE THIS GUY'S GOT SOMETHING TO SAY, I'LL GIVE YOU A BIT MORE CONTROL FOR A MINUTE, BUT REMEMBER **_THAT I'M WATCHING_**." Bill didn't completely give up control of Sans's body, just stopped talking to let him speak for a few minutes. A few minutes that Sans had no idea how to spend.

"H-hey…knock knock…?" Sans didn't have time to think of a good pun.

"Who is there?" Toriel followed along with the joke, whispering softly.

"T-that guy." Sans was mentally face-palming himself.

Toriel couldn't help but laugh a bit. "That guy who?"

"That guy who…always tells knock-knock jokes, at the door. I'm, uh, Sans…Sans the skeleton." He couldn't think of anything else to do other than an introduction, before explaining anything else.

"Ah…so it is you. I knew I recognized your voice from somewhere. Tell me, Sans, who's this little creature speaking from you?" Toriel tried her best to remain calm and get to the bottom of things, but anyone could she see was starting to tremble.

"This weirdo? Well…uh…" Sans couldn't just say 'I made a deal with _a literal demon of time and space_ so I could bring back you, and the rest of my friends, back from the dead. Oh, and you were all dead in the first place because of a time-travelling genocidal _devil child._ '

"…guess I was just in the wrong place at the wrong time." Sans sighed, he really needed to be serious now, if he had any hope of saving everyone. "Look, you need to find the souls and take-" The voice switching started again.

"SORRY PAL, TIME'S UP! WHAT MADE YOU THINK **_YOU WERE IN CONTROL_**?" Every time Bill's voice turned deep and bone-chilling, Sans's eye glowed brighter than it ever did before, as it was now fueled by the influence of two ridiculously powerful beings.

Asriel felt the soul inside him ache for justice. "What do you want with the souls?! My dad…Asgore…he's gonna stop you!"

"AWW, LOOK AT THIS KID, SO FAITHFUL TO HIS FAMILY. I BET YOU'D HATE TO SEE ANY HARM COME TO THEM, HUH? KEEP THAT IN MIND WITH WHAT'S ABOUT TO HAPPEN NEXT, JUST KEEP YOUR FURRY LITTLE NOSE OUT OF MY PLANS AND YOU'LL BE HOME-FREE." The whirls of blue magic were summoned up again; and right before Bill/Sans teleported, "SEE YOU SOON!" was echoing through the entire house.

Meanwhile, a few moments later…

"Remember Papyrus, it's SUPPOSED to smell like burning!" Undyne instructed Papyrus as they proceeded with the cooking lesson.

"WELL, IT CERTAINLY DOES! WHICH IS WEIRD, CONSIDERING THE OVEN ISN'T EVEN ON YET…" Papyrus looked around the kitchen area curiously.

"What? I'm pretty sure that's not normal, even for MY house. Go see what's wrong, maybe it's just the fridge again…" Undyne walked to the other side of the kitchen.

Papyrus looked out one of the windows, after hearing what sounded like a scream. "AH, I'VE DISCOVERED THE PROBLEM! THERE SEEMS TO BE A LOT OF FIRE AND DESTRUCTION TAKING PLACE OUTSIDE AT THE MOMENT."

"What? What's going on!?" Undyne dashed to the nearest window, and she gasped. Weird creatures- that were nothing like the ones that had ever lived in the Underground- were all over the place, crawling and wreaking havoc.

"I never thought I'd really have to say this, but…we have to do something! It's time for us to fight, to defend everyone! That's what the royal guard is for!" Undyne practically jumped into her armor and grabbed her spear.

The Underground is usually so peaceful; it seemed like the only case where the Royal Guard would actually be needed is if a war broke out between humans and monsters again. Even after years of training and attacking humans, Undyne was scared. These creatures—whatever they may be—were nothing Undyne thought she'd ever need to fight. They weren't human; they weren't any type of monster she'd ever encounter before either.

And there was also the matter of Papyrus going into battle himself…he could fight, that was for sure. He probably could've even killed a human if he wanted to, but that was just the thing, he _didn't_ want to. There was no way Papyrus could ever give an opponent anything less than a smile and some light-hearted attacks, he could easily get turned to dust out there.

"Papyrus!" Undyne called just before they went into battle, she didn't have time to explain why he should stay behind—but she _did_ have the time and the power to watch out for him. "Don't let any of those freaks lay a finger and you, and don't hold back!"

"WORRY NOT, UNDYNE! THE GREAT PAPYRUS HAS BEEN TRAINING FOR THIS VERY DAY!" Papyrus opened the door; a blast of raging wind came bursting through. The two warriors looked at each other and nodded. Undyne flashed a threatening grin at the twisted creatures lumbering around, and Papyrus ran right beside her, fully prepared for any hell they would have to go through in order protect everyone.

The two of them were filled with DETERMINATION.


	8. Chapter 8

Some of Bill's monsters could be killed, some couldn't. At the very least, Papyrus and Undyne could cut off a limb or two, enough to slow down the opponent. They were trying to get to the source of all this destruction, and whomever-or whatever-it was very quick to send out a wall of monsters.

As much as Undyne would've loved to drop her spear and wrestle the biggest monsters to the ground, she left those ones to Papyrus, while she handled the smaller creatures. The less threatening an enemy looked, the more likely it was that Papyrus would spare it. And this was a situation where mercy was NOT an option.

But even so, it was almost energizing, racing through the rushing wind, jumping and flipping through the air, landing hits on powerful foes. Undyne easily cut through the enemies with her spear, and Papyrus sent out bone attacks, he could even use his signature "blue attack" on some of the creatures.

Weirdly enough, these monsters didn't have souls; they didn't turn to dust either. All you could hear when one died was a thud, and that was it. These creatures were definitely NOT Underground monsters.

Undyne realized she still had much to learn herself, she was so used to one-on-one fights that she didn't notice when she was being surrounded. Papyrus ended up saving her as much as she saved him.

As the two of them finished off the third wave of monsters, the wind started to die down, just enough for Undyne to see a familiar figure in the distance.

Undyne jumped on top of the last monster she defeated, and looked in the direction of the figure. "Is that Sans? He doesn't look...safe."

Papyrus jumped up next to Undyne and looked in the same direction. That really was Sans, and hovering above him was an ominous triangle shadow, that was slowly growing larger.

Undyne had to hold Papyrus back from running of to save his brother on his own. Little did she know, Sans had watched Papyrus die before, and after discovering this, there was no way Papyrus was letting the roles be switched, especially when he could do something about it.

But it only took Undyne a second to say her piece: "No way, I'm coming with you." She flashed another grin, and with that, they dashed towards the shadow.

A few moments earlier...

Toriel and her son ran towards the location of the souls as fast as they could, following trails of blue magic left behind by rapid teleportation. But at this point, all the speed in the world couldn't stop Bill from getting to his desired "power source."

"WELL, WOULD YOU LOOK AT THAT?" Bill called as Toriel and Asriel appeared from around the corner, "LOOKS LIKE I DIDN'T EVEN HAVE TO GET PAST THE KING, HE ISN'T HERE! DON'T MIND IF I DO, THEN!"

Bill, still in Sans's body, approached the souls. Free from their containers, the souls circled around, drawing themselves towards the nearest creature, which happened to be the triangle possessing the skeleton.

Asriel almost jumped out, attempting to push 'Sans' away from the souls, but Toriel quickly sensed the incoming danger and held her son back from harm's way.

It was like Bill already had the power he wanted before even absorbing the souls, the walls of Asgore's home instantly fell to the ground, another void opened up, and the whole Underground was soon swallowed in a reality-warping version of hell.

Bill didn't change form, or become the ungodly creature Sans was afraid he'd face. Instead, 'Sans' floated upwards for a bit one eye glowing a bright blue, until Bill finally left this body, and soon started growing in size, blocking the entire view of the sky out.

Sans fell to the ground, consumed by pain coming from all the magical energy Bill made him use. The phrases he had heard in his dream were now being played out in front of him.

"You should've stopped me when you had the chance…" "We won't let you get away with this…!" Sans now knew the owner of the unrecognizable voice. Asriel.

Sans struggled to get up, every bone aching, but he wouldn't let things turn out like they did in his dream.

Breathing heavily, Sans barely managed to cut off Bill's last sentence, he turned to Toriel and Asriel. "Run." He pointed a shaky hand in the opposite direction, "run, and go find Asgore. Look for shelter, hide anyone and anything you can."

"But what about you…?" The mother and son said at the same time, although they were slowly backing away in fear.

Sans shook his head. "Don't worry about me; I'll take care of this guy." The pair still looked concerned, but nodded obediently and took off.

"OOH, IS THIS A CHALLENGE? HOW FUN! BUT FIRST, THERE'S A FEW TIIIIINY LITTLE CHANGES I NEED TO MAKE." From the void that was still opened, bizarre creatures of all shapes and sizes poured out. "HAVE FUN, YOU GUYS! THIS IS _MY_ WORLD NOW; FEEL FREE TO SPREAD ALL THE CHAOS YOU WANT!" Bill's monster friends let out an ungodly cheer in response, and they ran away in all directions.

"O…kay…" Sans muttered, trying to hide his panic.

"OH, THAT'S NOT IT, JUST WAIT UNTIL YOU GET A LOAD OF THIS ONE!" Bill raised his hand, and above his palm was the human. Frisk—Chara—whoever they really were, floating motionless and limp. "DID YOU REALLY THINK I'D PASS UP THE OPPOURTUNITY TO HAVE A SOULLESS EVIL SPIRIT ON MY SIDE?" He then _separated_ Chara from Frisk, dropping their body to the ground, while still holding what Chara truly was.

For the first time, Sans saw Chara for what they really were: a dark, wispy evil spirit, with the face of a gleeful and demented child. Giggles erupted from Chara, growing more shrill and persistent by the second. No soul, no desire for emotions, no desire for anything except the destruction of all humans and monsters alike.

But Sans had technically fought Chara before, he could do it again, couldn't he?

"BEFORE YOU GET TOO EXCITED—NO, YOU WON'T BE FIGHTING THIS ONE. YOU'VE HAD ENOUGH OF THIS DEMON ALREADY, HUH? I'M GOING TO HAVE THIS LITTLE GUY RIGHT HERE—"He lowered Chara to the ground—"TAKE CARE OF ANYONE WHO _WON'T_ SUBMIT TO MY TYRANNICAL RULE!"

As horrified as he was, Sans couldn't take his eyes off of Chara, the one who had taken all his friends and family away from him so many times, the one that possessed Frisk and forced them to do horrible things time and time again.

"LET'S GET THIS BATTLE STARTED, SHALL WE?" Bill rubbed his hands together, engulfing them both in blue flame. Sans's eye began to glow brightly, fully prepared to make the first attack…until he heard a familiar voice.

Papyrus and Undyne were dashing forward, attacks ready. "DON'T WORRY BROTHER! WE'RE GOING TO SAVE YOU!"

"Papyrus!?" Sans turned around to see his brother, along with Undyne, trying to save him. "No! Don't-"

Bill saw them almost immediately, "OH, THAT'S GOING TO BE A BIT OF A PROBLEM, ISN'T IT?" He quickly shot some blue fire towards the running figures, intending to trap them in a wide circle, but only Papyrus got surrounded by this magic wall. With a few more snaps of Bill's magic, false images of a certain location and particular people appeared within the circle.

Papyrus now faced a hallucination-image of the bridge just outside of Snowdin—the one where he faced the human—and saw himself along with said human. The child was slowly approaching, while Papyrus had his arms wide open, waiting for a hug, saying that anyone could be a good person if they just tried, that he would help this strange human get their life back on track. And then one swish of the knife is all it took for Papyrus to turn to dust…Bill's hallucination was forcing Papyrus to watch _his own death._

But that wasn't the end of it, as the howling wind died down and the human passed through the bridge, sobs could be heard. The scene panned over to the opposite side of the bridge, where Sans had just witnessed all this take place.

"T-that. Little. B-bastard…" Sans muttered to himself between sobs, "This…this is why I don't make promises…! Taking my only family…I can't-I can't…I can't just stand around anymore." He walked over to where Papyrus was standing not too long ago, picked up his red scarf, and buried his face into it, sobbing all over again. Soon, angry wisps of magic could be seen coming from Sans's eye, "I-I'll stop that little demon…if it's the last thing I do…! I can't—I won't—let them get away with this. " He fell into the snow for just a moment, before teleporting away.

The vision was now gone, but the memories were imprinted in Papyrus's mind. He shook, speechless, and backed up, almost hitting the blue wall. "No…No…That couldn't be…that's not what…happened, is it…? Is it!?"

It was, as much as Sans wanted to protect his brother, the truth would've been revealed eventually, maybe not about the timelines, but the events that took place. Papyrus's death, Sans's reaction, and what followed after that.

The hallucination then continued, beginning to show the battle between Sans and the human.

"Nonono…please…no…" Papyrus covered his head, trying to block out the image. "I'm sorry, I'm sorry…I'm so, so sorry…"

And then a spear suddenly cut through the hallucination, Undyne had flipped over the wall, and was now banishing the flashbacks.

"Papyrus, Papyrus, are you okay!?" Undyne rushed over as soon as the job was done, dropping her spear and shaking his shoulders, but Papyrus was trapped in a state of shock, whispering "I'm sorry" over and over again.

Meanwhile…

"Papyrus! Undyne! What did you do?!" Sans screamed at Bill as the circle of fire was formed.

"DON'T WORRY ABOUT THAT RIGHT NOW, WHAT YOU SHOULD BE WORRYING ABOUT RIGHT NOW IS _**YOURSELF**_." Suddenly, the land they were covering broke off into a separate circle, and Bill flew them far up off the ground, he clapped, and then the surrounding world turned into nothing but a dark void.

Sans's magic was now going crazy, nearly spiraling out of control. Both creatures in this battle had blue-colored magic, and both were practically wrapped up in it now. The difference was that, with the souls, Bill didn't have to try as hard.

"Let's go." Sans whispered, shooting a gaster blaster straight at Bill, but he simply _created a hole in himself_ and let it pass through. The void surrounding them now turned into flashes of moments from Sans's fight with the human, whirling around and creating an insane amount of noise.

"I CAN TELL YOU'RE AWFULLY DETERMINED, I DON'T BLAME YOU. DETERMINATION IS WHAT GIVES ONE POWER IN THIS UNIVERSE, AND BELIEVE ME, I HAVE ALL THE DETERMINATION I NEED TO GET WHAT I WANT." Bill sent forth a few small monsters, ones that moved rapidly towards Sans, in return, he shot a few bone attacks through the creatures, killing them instantly.

"YA SEE, WE'RE NOT THAT DIFFERENT, YOU AND ME. CRAZY POWERFUL, DETERMINED TO FIGHT FOR ONE PURPOSE…OKAY, WELL, MAYBE THAT'S IT." Sans growled, he knew he was nothing like this twisted creature. What Bill was doing is no better then what Chara had been attempting, and Sans wasn't going to be fooled into thinking otherwise.

In his fury, Sans had summoned up a whirl of magic around himself, and ended up creating several beams rapidly approaching the yellow triangle. Behind Bill, Sans could see the image of himself finally being killed by Chara, on repeat, again and again, never stopping.

But all Bill had to do was temporarily shrink his size in order to avoid them.

"YOU AND EVERYBODY ELSE HERE WOULD ACTUALLY FIT IN PERFECTLY WITH MY FRIENDS; WE'RE ALL FREAKS, IN ONE WAY OR ANOTHER, THOUGH I STILL DON'T UNDERSTAND WHY SOMEONE WOULD RISK THEIR LIFE JUST FOR A SIBLING. MAYBE YOU CAN EXPLAIN THAT TO ME LATER!" Bill shot a beam straight from his eye, one that Sans just barely dodged.

He didn't know why he hadn't figured it out sooner: soulless. Bill was soulless. Just like Flowey was…no chance of gaining any pity or begging for mercy here. It wouldn't matter to Bill who he killed, because in the end, he had no soul to feel remorse.

But the words "just for a sibling" angered Sans even more, to the point where he didn't even notice how much energy he was using up. Gaster blasters and bone attacks came raining in from all sides, but through a series of changing size, shape, dodging, or just pure being unaffected, not any of this attacks landed a single hit on Bill.

Sans fell to his knees, panting. "GETTING TIRED? I TOLD YOU, THE ONE WITH THE MOST DETERMINATION ALWAYS WINS. AND YOU—YOU DIDN'T EVEN HAVE ENOUGH TO STOP YOUR BROTHER FROM BEING KILLED IN THE FIRST PLACE! OR WAS DOOR LADY'S PROMISE REALLY THAT IMPORTANT TO YOU?"

"Urrrgh…!" Sans wanted to scream, but he no longer had the power to do even that. In just a few, futile attacks, Sans had been defeated.

"NOT GOING TO DODGE THIS TURN? THAT'S ALRIGHT; LET'S END THIS HERE AND _**NOW**_."

One magic blast from the side, and that's all it took to drain the 1HP Sans ever had.

"Ugh…Ugh!" Sans fell to his side, wrapping an arm around where he had been hit. "Urrghh…! No…! I…I. Can't. Lose. Now…!"

As Bill went on about how he and Sans could've been friends, the skeleton put a hand right over where his soul was, and felt it slowly breaking, soon it would shatter…and then he would turn to dust and die.

He felt lightweight; he felt his body fading away, his spirit draining, his soul cracking.

 _But it refused._


	9. Chapter 9

Frisk woke up on the ground outside, where all the chaos was taking place. It was a miracle no one had attacked them yet…but then again, Frisk already looked dead.

"Mmn…wha…what?" Frisk stood up, feeling…empty. They wobbled where they stood and glanced around the area, feeling absolutely nothing at all.

"Frisk!" Asriel called, running to his human friend. "Frisk…are you okay?! There was this weird triangle guy…a-and now there's this scary ghost-like thing that people have been saying is Chara…Never mind that, we have to get to the shelter!" Asriel took Frisk's hand and dragged them along, rushing towards the ruins—or at least—what was left of it.

It took the two of them a rather long time to reach the ruins. Asriel had to pull Frisk to hiding spots whenever one of Bill's monsters passed by, and the human didn't walk very fast. Asriel was out of breath by the time they reached the 'shelter' he and Toriel had earlier discovered.

Only half of the ruins had been knocked down, and Toriel's house remained intact. By Sans's instruction, they had been hiding every underground monster that could be found. But even so, the ruins had lost the liveliness it possessed before: The flowers and plants had wilted, the walls were a faded purple, and cracks had made their way into the floors. Frisk noticed this as Asriel brought them closer to Toriel's house, but said nothing. They had said nothing at all throughout the whole trip.

"Frisk, what's wrong?! You've hardly moved at all…" The goat child stopped walking and put his hands on Frisk's shoulders.

"Have to go…save everybody…have to do something. But why do I feel so…so…hollow?" Frisk swayed back and forth, they had a bit of determination left, enough to keep them standing. But most of this feeling was left in their soul.

And then Asriel remembered that he still had Frisk's soul. "Your...! Frisk, I'm sorry, I-I have it, that's how I'm like…this…right now." He was referring to his real form, not the flower one. "I'll give it back, hold on!" Asriel summoned Frisk's red soul out from his chest, and began to float it back to the human. "I'll go back to being a f-flower…but you're the hero everyone needs right now. Make me proud, okay?"

"Asriel…" Even with the soul between them, Frisk could feel their compassion flooding back already. They put their hands on top of the soul, stopping Asriel from pushing it any further. "It doesn't need to be like this…" Frisk then took hold of the soul, tearing it into two equal pieces, half and a half. They absorbed one half and pushed the other back to their friend.

"Frisk…I…how…?" Truthfully, having a half-soul didn't feel any different from a full one, maybe because the other half was so close by. Feeling the same, Frisk smiled.

"If I can piece my soul back together with determination alone, then I can break off a part to share with a friend, can't I?" They both knew which timeline Frisk was referring to.

Asriel couldn't stop himself from hugging the generous human, and he couldn't help the tears that came flowing forth either. "T-Thank you…so much…I…I really don't deserve this, not a-after all the horrible things I did…" Frisk held his friend closely, patting him on the back and hoping to provide some comfort.

"You didn't have a soul, you tried and you tried, but you just couldn't feel a thing." Frisk sighed, "That's how I felt, just a minute ago. I knew something was wrong, I knew my friends needed help. But I was…empty, I could hardly function; I could hardly care about anything. If you weren't there, I might've been wiped out by the first creature that came along. So…thank _you_."

Asriel was the first to back out of the hug. "Frisk…I have so many things to say, and so many questions to ask. But right now…" Asriel peaked back outside, where the entire Underground was in the process of being destroyed. "Your friends…our friends…they need you."

"But I can't do it alone" Frisk replied quickly, their words quiet and steady.

"I…I wouldn't be much help." Asriel muttered in response. "Your soul…it's so strong. Today, I've felt more fearless then I ever have before. It's not dying that I'm afraid of…I just…I just can't go back. I can't. Mom already found me, and right now she's looking for Dad. Those are the only people who need to see me…"

"Asriel, we're two halves of a whole soul. Both of our halves have enough determination to survive, but maybe not enough to stop…whatever is causing all this. Not on our own." Frisk quickly glanced outside and then looked back at Asriel, they didn't want to see more than needed. "Look, Chara…isn't a part of me anymore. I can feel it, but that demon's power helped me keep going. Now, our determination, our soul, our compassion…we can do this. Together. Like a team, like…siblings."

Asriel slowly began to smile, "Then…Then, I guess-"

"-I'm sorry, my children." Toriel's calm, patient voice came floating in from behind them. "But I cannot allow you to put yourself in harm's way again; I have already lost you both, once…I simply won't let you go again, just look at what happened after that!" Of course, Toriel didn't want either of them to actually look. They were only children, and children should never be exposed to such horrific sights.

"Mom." Asriel said firmly, tugging on Frisk's sleeve as he summoned up his half of the soul. "We…we have each other, we'll be fine." The human copied the goat child's actions.

"What on Earth…?" Toriel approached slowly, squinting at the soul pieces. "No, never mind that…we have to wait for Asgore. As much as I hate to say it, the Underground needs their murderous King right now."

"Mom." Asriel repeated, "If it weren't for this soul piece…if Frisk wasn't so kind…I'd be a flower again by now. Our soul can't be shattered; we can't be killed. I know you don't remember…I know you have no clue what I'm talking about right now…but, please…our friends need us. And with this type of soul, we're the only ones who can stop this madness."

"Asriel…I-" Frisk cut Toriel off, "I've done this before, defeated crazy-powerful monster gods, you can't remember, a lot of us can't…but we do…that's why…we need to end this together.."

"I cannot believe I'm saying this…but…something is telling me you speak the truth. I am trusting you both to look after one another, alright?" Both children nodded firmly, and gave Toriel a hug. "Good luck, my children…" Looking like she was about to cry, the goat mother rushed back into the depths of the ruins before she could change her mind.

Steeling themselves for battle, Asriel and Frisk slowly crept to the exit of the ruins (which, at this point, was just a big hole in the wall.) The human child suddenly blinked and took a few steps back.

"Frisk?" Asriel asked, quickly beginning to panic. "Is…are you okay?!"

Frisk recalled the sensation of something evil and dark being pulled from their body, followed by the ground around them rumbling, a certain skeleton being lifted into the air. Frisk didn't know how they saw this in a state of unconsciousness, but it felt so real. Too real.

"I just…some memories are flooding back now." Frisk shook their head and pointed to the sky, where a piece of ground could be seen floating, and it appeared to be surrounded by a force field of some kind. "Sans is up there, we need to help him, whatever the source of all this is…it's up there."

Asriel nodded, and offered a hand to Frisk, they took it, and together the two of them began to approach the floating platform.

Meanwhile…

Undyne was still trying to bring Papyrus back from his state of shock, the fiery wall had died down by now…but the images Papyrus had seen remained fresh in his mind.

"Papyrus, can you hear me!?" Undyne called, yet again.

"I'msorryI'msorryI'msorryI'msorry…" was all he could say.

All Papyrus could visualize was the memory of his brother finding him dead in that snowy area, the air thick with icy wind.

"PAPYRUS! YOUR BROTHER IS IN DANGER, WE HAVE TO DO SOMETHING!" Undyne had enough with trying to gently coax him out of his meltdown.

Those words called Papyrus out of his mental nightmare; the memory vanished, he blinked, and looked up at Undyne. "Y-Yes…WHAT ARE WE STANDING AROUND HERE FOR!? LET'S GO!" He jumped back up to his feet, and Undyne followed right behind him, not wanting to question his sudden change in behavior.

"Don't let me be too late… _please_ don't let it be too late…!" Papyrus whispered to himself as he ran, not yet noticing the raised piece of land.

That was then, and now…

"Hu…huh?" Sans felt his soul reform, all his energy coming back to him, and when he opened his eyes, he discovered that something—no—some _one_ was protecting him from further harm.

A small figure in a striped shirt stood in front of Sans, guarding him with their own soul, or at least…what was left of it.

"W-What? You haven't beaten this guy yet?" Frisk smiled, "C'mon, this werido's got nothing on you!"

"K-kid…your…" Sans stood back up, looking at the thin white line Frisk had created, the "shield" that was now blocking out Bill's voice and attacks.

The yellow demon was still as powerful as ever, hovering dangerously above them, but every attack—every word—was quickly repelled by what the human had conjured up.

"I-I can't hold this up for much longer, when I let go, triangle guy will probably attack you again. But you won't be alone this time." The ground started to vibrate with all the energy Frisk was putting into the shield, but kept smiling. Sans was now smiling too, glad to see his friend alive and well.

"We've got this, Frisk." Sans spoke confidently , "Let's give this weirdo a bad time." He began to summon up his magic again.

"Ready?" The child asked, Sans nodded, and Frisk brought their arms back to their sides and dropped the shield.

Now, the real battle was beginning.


	10. Chapter 10

When the shield dropped, it rippled outward—hitting Bill—but certainly not harming him.

"HAHA, YOU THINK THAT'S REALLY GOING TO STOP ME? I DON'T KNOW HOW YOU PULLED THAT OFF, BLANK-FACE, BUT REMEMBER _I_ STILL HAVE THE SOULS! AND UNLIKE YOUR LITTLE GOAT FRIEND, I DON'T HAVE A DESIRE TO FEEL "COMPASSION" FOR OTHER PEOPLE! WHO NEEDS ANY OF THAT WHEN YOU HAVE ALL THE POWER AND FREEDOM YOU COULD EVER WANT?" Bill made no move to attack; he saw no need to do so yet.

Frisk smirked, "If you're everything you claim to be, you'd know this isn't the first time something similar has happened." Truthfully, Frisk had no weapons to fight with; they would have to make do with creating shields whenever needed.

Sans wasted no time talking to the yellow demon, and with his strength renewed, mass amounts of magic took mere seconds to summon.

"ALRIGHT, WELL, AT LEAST THERE'S TWO OF YOU NOW, THAT'LL SURE MAKE THINGS A LOT MORE INTERESTING!" Although Bill had the power to vaporize the two of them right then and there, he felt that making them face off against his monsters would be a lot more entertaining to watch.

One flash of the blue magic Sans had summoned, and all the monsters were wiped out. Even Bill seemed a little smaller after the blast.

It took no sound or words for Frisk to know their skeleton friend was filled with determination.

This alarmed the yellow demon far more than he was willing to admit, and he immediately fired back a beam of pure energy _from his eye_. Frisk was ready to jump in and create another shield, but Sans deflected the attack with a gaster blaster, the two blindingly-bright rays of magic clashing.

"JUST GIVE IT UP, SKELE-PUN; YOU CAN'T KEEP DOING THIS FOREVER!" This was true, but Sans wasn't about to let that stop him.

"I don't care…if I have to stay like this forever." He wasn't able to say very much at one time, having to focus on keeping Bill's magic from getting too close. "I won't let you…destroy everything we know."

While Bill started to monologue about how hopeless a fight with him was, Frisk carefully stood below the beams being shot, they raised their half-soul to the middle of the gaster blaster, if it weren't for determination, the soul would've broken as soon as it plunged into the beam.

 _But it refused._

And it refused when it pushed Sans's attack towards Bill, and it refused when the "battlefield" started to shake from all the power being used.

They finally landed a hit on Bill, and he shrank back down to his normal size, the souls spiraling out of him.

"WHAT? NO! YOU GET BACK HERE!" Bill reached for the souls, trying to absorb them again.

Frisk was quick to act; they had been planning for this very moment. "Asriel, _now!"_ Their words echoed, causing everyone in the room to look for any sign of the goat child.

Asriel came spiraling in from one side, holding the six jars that had once contained the human souls; he got one soul back in its jar and threw half of the remaining ones to Frisk.

What happened next was almost comical, a tiny Bill chasing the two children while they ran around, recapturing the souls, Sans took a moment to watch and actually laugh, recovering from the impact of his last attack.

Finally, all the souls were back in their jars, now Frisk and Asriel stood side by side, giggling.

"NO… _ **NO! I STILL HAVE POWER! I CAN**_ …" Sans' eye began glowing again-he turned Bill blue-subjecting him to gravity and slamming the triangle to the ground.

Frisk had an idea, and handed their half of the souls to Asriel. They created another sort of barrier, except it was around Bill, in a square shape, and he could still be thrown around.

"Nice, kid." Sans smiled at his human friend and moved his hand upwards, hitting Bill against the upper wall Frisk had created, and proceeded to throw the demon against each wall multiple times. Weakened, Bill was unable to fight back.

Asriel slightly winced seeing Bill so brutally thrown down, and couldn't help but laugh. The portal Bill had created started to open again, sucking in the demon and all his monsters…and all the wreckage he had created.

Frisk was the first to notice this, and put a hand on Sans' arm to make him stop. "That's enough, he gets the point, and we know how to show mercy when needed, right?" Frisk smirked, and Sans let Bill turn from blue back to yellow.

The triangle was in shock, and retreated into the portal without another word. Finally, it was over.

The platform their battle had taken place on began to shake, and started to fall. Asriel quickly took Frisk's hand and they floated upwards with their soul, pulling Sans along with them.

The wind had now fully died down, and the three of them laughed while falling, both from relief and joy, it wasn't long until their friends waiting below heard them.

It was clear that everything had gone back to normal, buildings were back in place, monsters roamed freely again…it was almost like nothing had happened at all.

And the best part?

Although their adventure was not yet over, the barrier had been destroyed.


	11. Chapter 11

Toriel waited in the ruins, glancing worriedly out the gaping wall every few seconds. She was too far away to see what was happening, but she could feel it in the air—a shift, a change—signaling that things could go very wrong, or very right, in just a matter of minutes.

Footsteps sounded behind Toriel, at first she was surprised…but didn't need to turn around to know who the footsteps belonged to.

"Tori." Asgore's deep, gentle voice floated into the room.

"…and where have you been, Dreemurr?" The Queen refused to face him.

The King heard bitterness in his ex-wife's voice, and hung his head. "Dr. Alphys told me something was wrong, and that she was about to evacuate everybody…the ruins were the only location she was not able to contact, so I came here myself."

"…" There was really nothing wrong with what Asgore had done this time, but Toriel's bitterness came from previous events. "The Underground needs you, and yet again you elected to act like a coward rather than fight for your people?"

Asgore could sense the fear in Toriel's voice, and barely stopped himself from giving her a hug. He sighed, "Yes, perhaps that was a bit foolish of me…but look!" He pointed out the wall, which was now slowly starting to repair along with everything else. "It appears everything has worked itself out after all."

While she was relieved, this didn't make Toriel feel much better about Asgore. "Our _child_ went out there to fight, Asgore, our _child!_ " The Queen didn't bother explaining how that was possible; she still didn't know the answer to that herself.

"What…? How…? Asriel…" Asgore whispered these words to himself, and Toriel gave him time to let the fact sink in. He remembered the unbearable grief he felt losing both his children, the pain of not being able to stop that tragedy from happening.

The hole in the wall was almost fully closed now, but there was just enough space for Asgore to make it out, closely followed by Toriel.

Meanwhile…

As Sans, Frisk, and Asriel fell back towards the ground, several bones and spears flew past them, and immediately knew who this was the work of.

"Papyrus, Undyne, we're okay!" Frisk called to them, laughing, a few more projectiles flew before eventually stopping, just as the three of them hit the ground.

Papyrus's first instinct was to hug his brother, and that's just what he did. Undyne stared at the goat child she hadn't seen in what felt like centuries, and then enveloped him in a hug. "You little-! I don't even want to know how on earth you're here now; I'm never letting you go!" Asriel giggled, and reached out a hand to Frisk, turning the hug into a group hug.

Asgore and Toriel were now making their way over, and the King called: "My son; is that really you?" Despite what Undyne had just said, she knew the King and Queen needed to see their child most of all. Asriel wriggled out of the hug and ran towards his parents, jumping towards them and quickly being caught in mid-air.

Undyne now let go of Frisk as well, and looked in the opposite direction. "I'm going to go look for everyone else, and by everyone else I mean Alphys!" She ran off, leaving everyone else to their reunions.

"I'msorryI'msorryI'msorryI'msorry…" Papyrus was remembering the images all over again, and it didn't take Sans very long to realize what his brother had gone through while he was fighting Bill, Papyrus didn't speak like that unless something was _really_ wrong. They were both crying, but mostly from relief. "I-it's okay, bro…Its okay," Sans replied quietly.

Toriel and Asgore, for the first time in a while, were close to each other once again. The whole family was overjoyed to have each other back, right now, how or when or who didn't matter. The strange creature causing this whole mess was gone, and in the process the King and Queen had gotten their child back.

Any words of joy were cut off when Undyne started running back, followed by Alphys, everyone turned to see what the two of them had to say.

"S-sorry for my absence…" Alphys stuttered, "But…now the barrier is gone…!"

A silent, collective gasp could be sensed from everyone. No one was quite ready to leave yet, but soon-

-And then an eerie voice floated in, sending shivers through those who were anyone near.

A wispy, almost ghost-looking creature…with the face of a child and a knife in hand.

" _Ehehehehe…did you really forget about_ _ **me?"**_


	12. Chapter 12

In their excitement, the monsters had indeed forgotten about Chara.

Toriel and Asgore moved to guard their son from what used to be their adoptive child, though they were unable to recognize the "human" at this point.

" _Heh…that overpowered triangle doesn't control me. Although…he did do me quite a favor. Maybe he'll come back after I'm finished here…but now…"_ The eerie, childish laughter started up again. " _The barrier is down, and humanity will be at my mercy. But of course, one or more of you idiots is going to try and stop me, aren't you?"_

Chara was right; Frisk stepped forward, although they weren't sure where to go with this. Even if the child did have any idea of how to calm down the demon that once possessed them, everyone else held Frisk back before they could step towards danger.

" _That's right, protect your little human friend, protect the one who gave you a happy ending, the one who reset it all, only to come back and kill_ _ **every. Single. One of you."**_ Chara smirked and turned towards Sans, " _you know all about that, don't you? And yet you keep trying, heh…"_

Everyone's gaze turned to Sans, and he lowered his head. He couldn't just tell everyone the truth at a moment like this, not now.

Chara took a twisted delight in seeing everyone so confused; they could attack while everyone had their guard down. It would be swift, painful for the monsters, but a wonderful experience for the demon child. The only one who wouldn't let themself be distracted was Frisk, or so it appeared.

"That's enough, Chara." Asriel walked past his parents and revealed himself to his "sibling." Chara began to cackle all over again.

" _And you, Asriel, you couldn't even fulfill my final wish and let me do what I want. You've always been a coward, a crybaby…what makes you think you could change anything_ _ **now?"**_

Frisk was about to step forward and join Asriel, but then Sans lifted his head, and anyone could see he was shaking with anger. Even angrier then he was when fighting Bill.

Chara stopped laughing as they were turned blue and started to be float in the air. " _Oh, this again? Hehe…you know how much LOVE I have, even if you were to kill me, it would take so, so long…and with my determination…_ _ **I'll come back."**_

But they wouldn't, the determination Chara was feeding off of throughout the timelines belonged to Frisk, the demon child that stood before them now didn't have a save point to go back to.

"Y'know…it's a beautiful day outside." Sans ignored Chara's threat and went through his usual lines, while everyone else was too surprised to say anything. "Birds are singing, flowers are blooming…"

Frisk got an idea, and pulled Asriel over to where Sans was. After some whispering, the three of them began to laugh at whatever it was Frisk had come up with. As for the monsters surrounding them, it was almost as if question marks were above their heads.

Sans approached the floating Chara, going on with his mini-monologue. "On days like these, kids like you should…" He turned to look at Frisk, they smiled and nodded at each other, and then the skeleton flew Chara as far to the side as possible, while Asriel and Frisk cheered.

"Geeeeeeeeet dunked on!" The two children yelled this as the demon was slammed to the ground, the smoke they were composed of evaporating with a screech, which every monster pretended not to be startled by.

Sans turned back around and realized he had a huge explanation to make, so he started which what just happened. "No soul, not enough determination to come back to life. At least, not as much determination as this kiddo right here." He pointed to Frisk, who was looking happy and troubled at the same time.

Clearly, everyone was still massively confused, and rightfully so. Explaining the whole situation: the timelines, who exactly Chara and Bill were, Asriel's reappearance…these would all have to wait, and at this point, there was a silent agreement upon all of this.

But now, the barrier was down, and everyone stepped into the sunlight. A bright future awaited; one that didn't carry the fear of resets, one that guaranteed a happy ending for all who deserved one.

And as for the human souls Asriel and Frisk were still carrying? Asgore decided to give them back to the human bodies that originally owned them, bringing those children back to life as well.

Bill was no longer a threat, wherever he was, he wouldn't be coming back anytime soon.

At least, that's what everyone thought.

P.S Before I publish the author's note, I'd like to give a special thanks to guest Skystarthecat, who left me a very nice review. I'd love to thank you personally, but since you reviewed as a guest, this is the best I could do. Thank you so much!


	13. Author's Note

This fic has been such a trip for me to write, you have no idea, it all started from a few posts on Tumblr, and here we are now. I really didn't expect my story to get this popular; or popular at all really. Thank you all so much, every review and follow has filled me with DETERMINATION.

With that being said, I would like to give special thanks to my friend The Shifting, as well as all of my regular reviewers, and anyone who took the time to speak with me. I'd also like to thank tumblr user cygniphantom for creating a lovely drawing illustrating a scene from chapter one, they're also currently working on an original comic called Undertales of Creation, which I encourage everyone to read.

For anyone who hasn't seen already, I recently published the first chapter of my next story, Choose One, which is based on the scenario in which Frisk has to choose only one of their friends during Asriel's boss fight. I've considered planning out a sequel to Deal With a Devil, but I feel like it would turn into a "Great Story With a Bad Sequel" too easily. I left the ending open-ended on purpose, and it is free to interpretation.

I also have a few more ideas for fanfics that I'll start to write sooner or later (mostly focusing around Flowey/Asriel and Chara, and if I put enough headcanons together for it, an underfell!AU fic.)

If any of you have any questions or comments, please don't hesitate to PM me or shoot me an ask at my tumblr true-pacifist-skeleton. I'm trying to be one of those writers who considers the opinions of their readers, it's the least I can do.

Again, thank you all so much for your support; and I hope you'll all continue to read my upcoming stories.

P.S. If anyone wants to draw or do a voice-over of any of the scenes in this fic, you have my full permission to do so! Just please send me the link and credit me once you're done, I'd love to see what people come up with for this.

Stay Determined!

-True Pacifist


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